Watch the trailer for This Is It. Courtesy of Sony Pictures
Compiled from hundreds of hours of rehearsal footage, This Is It documents the final weeks of Michael Jackson's life, as he prepared to put on the biggest shows of his career at London's O2 arena.
BBC Entertainment correspondent Lizo Mzimba was at the London leg of the movie's international premiere, held simultaneously in 19 cities worldwide. Here is his verdict.
While a fascinating insight into Michael Jackson's tour preparations in the weeks leading up to his death, This Is It never quite manages to be as compelling as many fans will want.
After weeks of hype and expectation, the movie - pieced together by Jackson's creative director Kenny Ortega - gives a broad impression of what the final show would have been like. But it only occasionally makes you forget you're watching a rehearsal.
Fans will see Jackson directing rehearsals and planning dance sequences
The fault doesn't lie with the film makers. This was a work in progress. And not all the elements that would have eventually been included in the concerts are present.
What does come across, though, is Michael Jackson's passion for detail. They were his songs, and he knew exactly how he wanted to perform them.
Particular highlights are Wanna Be Startin' Somethin' (which would have opened the King Of Pop's shows at London's O2 arena), Smooth Criminal and Beat It.
A lot of attention is given to the filmed elements Jackson was creating to accompany the songs. Much effort was put into a creepy, 3D graveyard sequence for Thriller, and a young child playing in a forest for Earth Song.
We never get to see how these sequences would have actually been integrated into the show, but there's no doubt they would have dramatically enhanced Jackson's onstage performance.
And, despite his age, his dance skills didn't seem to have diminished. What the film can't tell us, however, is whether he truly had the stamina to make it through 50 shows.
Even so, apart from appearing noticeably thin, there were no particular signs of health problems.
Of course, the nature of the movie means it sometimes lacks atmosphere. It's difficult enough to portray the energy and excitement of a live concert on film, doing it only with rehearsals is even tougher. Still, Michael Jackson was a charismatic enough performer that his undoubted talent and enthusiasm do come across.
As a record of the comeback concerts that never were, This Is It is inevitably lacking.
As a glimpse into the workings of one of music's greatest stars, it's unique.
The critics give their verdict on This Is It:
DAVID GRITTEN - THE TELEGRAPH
"As This Is It progresses, the focus shifts to Jackson's struggle to stay on top of this hugely demanding show. At times, when he performs Billie Jean and Man in the Mirror, his authority and remarkable stage presence carry the day.
"Yet in other moments he seems petulant, tentative and even frail. He interrupts one routine to deliver a curious rant about his earphone, through which he can hear his back-up singers, causing severe pain in his inner ear."
"I can simply report that it isn't too bad at all. It's pretty much unadorned rehearsal footage, artfully stitched together to create complete song sequences; and since the O2 gigs were intended to present his crowd pleasing hits, they're all here in their toe-tapping glory.
"Still, this could have been a lot worse. It's a bit much to claim it's any kind of viable substitute for the live show, and since Jackson avoids conversation as much as is humanly possible it's also a bit much to claim we get to know anything more about how he ticks. But This Is It is a testament of a kind, and one that is no disgrace to his memory."
"As a corporate act of damage limitation, the Michael Jackson concert film This Is It is appropriately engineered as an occasionally inspired but mostly neutral movie-going experience.
"Songs from across the eras, from Wanna Be Starting Something through to They Don't Really Care About Us, burst to life with a wanton percussive energy. While even when standing still Jackson has the charismatic mien of an instinctive dancer, one whose body posture suggests that a rhythmic leg-twist, a head-nod, or a hip-flick is only seconds away."
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